And even if GOS doesn't support your device (due to minimum security requirements) why not use upstream LineageOS?

Because upstream LineageOS doesn't support microg out of the box. You can install it but it needs signature spoofing to pass Google's SafetyNet garbage. Bonus point for some roms that allow you to relock the bootloader after the install (iodéOS, CalyxOS).

	▲	wolvoleo 9 hours ago \| parent \| next [-]
		Lineageos supports signature spoofing for microG these days! It did take them a long time to come around but they did in the end.
	▲	ForHackernews 4 hours ago \| parent \| prev [-]
		/e/OS also supports locked bootloaders for devices that have official builds (a smaller subset than the ones with community builds)